The Scenario
You are a SaaS ops manager. Your product uses Postmark's inbound email processing. Over the past two weeks, the same 50 spam domains have been hammering your inbound address with junk that creates noise in the support queue and occasionally triggers automated responses to garbage senders.
The domains are already in a Google Sheet, column A. You need Postmark inbound block rules for all 50 of them before the next batch hits Monday morning. You also need the rule IDs written back into column B so you can reference them if a rule needs to be removed later.
The slow version:
- Look up the Postmark inbound rules API
- Write a loop, call the API once per domain, handle errors
- Copy rule IDs from the API responses into the sheet
- Realize the API returned an error for 3 domains because they were formatted as full email addresses instead of bare domains
- Fix them and re-run
- An hour of plumbing for a list that should have taken five minutes.
The fast version is one prompt.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent inside your spreadsheet that reads the domain list and creates the Postmark inbound rules for you, with rule IDs written back per row.
Open the SheetXAI sidebar and type:
For each domain in column A of the 'Spam Domains' sheet, create a Postmark inbound rule to block that domain and write the returned rule ID into column B. Write 'Error: [reason]' if a row fails.
SheetXAI reads all 50 domains, calls the Postmark inbound rules create endpoint for each one, and writes the rule IDs back. Column B is your reference log.
What You Get
Fifty inbound block rules created in Postmark, with rule IDs in column B:
- Rule IDs for successful creates — reference these if you need to remove a rule later
- Error reasons for any failures — specific enough to fix and retry
- The domain list is now the block rule inventory for the inbound stream
You never opened the Postmark dashboard. If a domain gets acquired by a legitimate company next month and you need to unblock it, the rule ID is right there in column B.
Want to list all existing inbound rules before you create new ones, to avoid duplicates?
List all existing Postmark inbound rules and write the rule pattern and rule ID into columns D and E of the 'Spam Domains' sheet.
What If the Data Is Not Quite Ready
Spam domain lists are messy by definition.
When some rows are full email addresses instead of bare domains
The list was assembled from bounce logs and some entries look like spam@malicious.example.com instead of malicious.example.com.
For each row in column A of the 'Spam Domains' sheet: if the value contains an '@' symbol, extract just the domain part. Then create a Postmark inbound rule for each domain and write the returned rule ID into column B.
When the list has duplicates from multiple team members contributing to the sheet
The same domain appears in rows 12 and 38 because two different support reps added it independently.
Deduplicate column A of the 'Spam Domains' sheet, keeping the first occurrence of each domain. Then create a Postmark inbound rule for each unique domain and write the rule ID into column B.
When you want to check which domains already have a block rule before creating
Some of these might have been added manually to Postmark last week by a developer.
List all existing Postmark inbound rules and check column A of the 'Spam Domains' sheet against the returned rule patterns. Write 'Already blocked' in column B for any domain that already has a rule. For the remaining rows, create new Postmark inbound rules and write the returned rule ID into column B.
When you need dedup, format normalization, duplicate check, and rule creation all in one shot
The list is a mess and Monday morning is close.
In the 'Spam Domains' sheet: for any row in column A that contains '@', extract the domain. Remove duplicate domains, keeping the first occurrence. Check each domain against the existing Postmark inbound rules. For domains already blocked, write 'Already blocked' in column B. For the rest, create a new Postmark inbound block rule and write the returned rule ID into column B. Write 'Error: [reason]' for any that fail.
The pattern: instead of cleaning the list, checking for duplicates, and creating rules as three separate steps, you ask for all of it in one prompt.
Try It
Get the 7-day free trial of SheetXAI and open your spam domain list, then ask it to push the block rules to Postmark. The Postmark integration is included in every SheetXAI plan. For related workflows, see how to manage Postmark suppression lists from a sheet or the Postmark in Google Sheets overview.